1. Field of the Invention
The present invention relates to an image recording apparatus which exposes a photosensitive material to for an image.
2. Description of the Related Art
A digital photo printer becomes commercially practical as a printing device utilizing a digital exposure technology. In the digital photo printer, the image recorded in a film is photoelectrically read, the read image is converted into a digital signal, various kinds of image processings are performed to obtain image data for recording, scanning exposure is performed to a photographic paper with a recording light beam modulated according to the image data to record the image (latent image), and development processing is performed to the latent image to output a print (photograph).
Basically the digital photo printer includes an input machine having a scanner (image reading device) and an image processing device and an output machine having the printing device (image recording apparatus) and a developing device.
In the scanner, projection light of the image taken in the film is photoelectrically read by an image sensor such as CCD and transmitted in the form of the image data (image data signal) of the film to the image processing device. In the image processing device, the predetermined image processing is performed to the image data and transmitted in the form of output image data for image recording (exposure condition) to the printing device.
With reference to the printing device, for example, in the case where the printing device is one which utilizes the light beam scanning exposure, the scanning exposure is performed to the photographic paper with the light beam to form the latent image in such a manner that the photographic paper is scanned and fed in a sub-scanning direction orthogonal to a main scanning direction while the light beam modulated according to the supplied image data is deflected in the main scanning direction. On the occasion, the back print is recorded on the back side of photographic paper, and it is sent to the developing device.
In the developing device, the predetermined development processing and the like are performed to the exposed photographic paper to make the print in which the image taken in the film is reproduced.
In the image recording apparatus, after a long sheet of the photographic paper wound in a roll shape is cut in a predetermined length to form one sheet-like photographic paper, the image recording is continuously performed in such a manner that the main scanning of the photographic paper is performed with the light beam while the photographic paper is fed in the sub-scanning direction.
In the image recording apparatus, two pairs of feeding rollers are provided on an upstream side and a downstream-side in a feeding direction while sandwiching an exposure position. During the image recording, the two pairs of feeding rollers feed the photographic paper while maintaining planarity of the photographic paper by nipping the photographic paper.
In the image recording apparatus, in order to secure the planarity of the photographic paper at the exposure position, it is desirable that the pairs of feeding rollers, which are arranged in immediately before and immediately after the exposure position, are approximated to the exposure position as much as possible. However, there is a limitation of the approximation to the exposure position due to a size of roller diameter of the pair of feeding rollers and the arrangement and structure of a driving system for driving the pair of rollers.
Accordingly, in the image recording apparatus, there is a possibility that uneven exposure is generated, because a front end of the photographic paper becomes free and the photographic paper is curled after the front end of the photographic paper passes through the pair of feeding rollers located on the upstream side of the exposure position in the feeding direction until the front end of the photographic paper reaches the pair of feeding rollers located on the downstream side of the exposure position in the feeding direction.
Therefore, in the conventional image recording apparatus, as illustrated in FIG. 13, a sheet-like photographic paper A is nipped by a pair of feeding rollers 100 on the upstream side in the feeding direction and a pair of feeding rollers 102 on the downstream side, which are located across an exposure position P, thereby the photographic paper is accurately fed. Further, while a flatter guide 104 supports a back surface of the photographic paper A in the vicinity of the exposure position P, a pressing roller 106 provided between the pair of feeding rollers 100 and the exposure position P abuts on an emulsion surface of the photographic paper A. As a result, the photographic paper A is prevented from rising, and the image recording is performed well.
In the conventional image recording apparatus, in the case where the photographic paper A having a predetermined thickness enters the position between the pair of feeding rollers 100 on the upstream side in the feeding direction, between the pair of feeding rollers 102 on the downstream side in the feeding direction, or between the flatter guide 104 and the pressing roller 106 and in the case where the photographic paper leaves the position between the pair of feeding rollers 100 on the upstream side in the feeding direction, between the pair of feeding rollers 102 on the downstream side in the feeding direction, or between the flatter guide 104 and the pressing roller 106, sometimes the uneven exposure (uneven print density) is generated due to a fluctuation in load which is caused by shock, vibration, position shift, or the like.
Therefore, there has been proposed an image recording apparatus in which, in order to prevent the uneven exposure (uneven print density) generated by the fluctuation in load which is caused by the shock, when the photographic paper A enters and leaves the pair of feeding rollers 100, the pair of feeding rollers 102, or the pressing roller 106, while movable nipping rollers constituting the pairs of feeding rollers 100 and 102 are retracted from fixed rollers of the pairs of feeding rollers 100 and 102, the pressing roller 106 is separated from the flatter guide 104 to prevent from generating the shock (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2000-206638).
In the image recording apparatus described in JP-A No. 2000-206638, when the photographic paper A enters and leaves the pair of feeding rollers 100, the pair of feeding rollers 102, or the pressing roller 106, even if the pressing roller 106 is separated from the flatter guide 104 while the movable nipping rollers are retracted from the fixed rollers, in the case where clearance (separation distance) is small in the separating action, the end portion of the curled photographic paper A collides with the roller to generate the fluctuation in load. As a result, there is a possibility that the high-quality print can not be obtained because the uneven exposure is generated.
In the image recording apparatus described above, when the photographic paper A is placed on the fixed roller, the movable nipping roller is pressed against the photographic paper A to nip the photographic paper A, or the movable nipping roller is separated from the photographic paper A. When the photographic paper A is placed on the flatter guide 104, the pressing roller 106 is pressed against the photographic paper A to nip the photographic paper A, or the pressing roller 106 is separated from the photographic paper A.
In the image recording apparatus described above, when action speed is too fast in pressing the movable nipping roller against the photographic paper A or in separating the movable nipping roller from the photographic paper A, or when the action speed is too fast in pressing the pressing roller 106 against the photographic paper A or in separating the pressing roller 106 from the photographic paper A, there is a possibility that the uneven exposure (uneven print density) is generated by the fluctuation in load. Further, in the image recording apparatus described above, when the action speed becomes slow in pressing the movable nipping roller or the pressing roller 106 against the photographic paper A or in separating the movable nipping roller or the pressing roller 106 from the photographic paper A, there is a problem that exposure processing speed is decreased to decrease the throughput capacity.